3 “barbaric” reasons why some animals resort to cannibalism – toads, frogs and sharks

“Cannibalism” evokes a visceral reaction in us, conjuring up images of barbarism and despair. However, for many creatures in the animal kingdom, eating one’s own is a surprisingly common and often strategic behavior.

Sometimes eating one’s own relatives is motivated by a simple but necessary race for survival, while other times it is a creepy practice that some animals engage in after mating.

Here are three animals—tiger sharks, green and gold bells, and cane toads—whose cannibalistic tendencies serve a vital purpose.

Sand sharks – birth is a battle to be won

Sand tiger sharks (Carcharias taurus), they have an unusual reproductive strategy that begins with a cannibalistic showdown in utero. Female sandbar sharks often mate with multiple males, resulting in embryos from different fathers.

Once the largest embryo in each of the mother’s two uteri reaches a certain size, it begins to feast on its smaller siblings in a process known as “embryonic cannibalism.” While a mother can carry embryos fertilized by multiple fathers, this fierce competition ensures that only one father’s offspring is born.

The researchers used DNA profiling to investigate this phenomenon, examining the genetic relationships between mothers and their hatchlings. The results revealed that while 60% of females mated with multiple males, only 40% of litters contained offspring from different fathers, according to a June 2013 paper published in Biological leaves.

In most cases, the hatchlings that survived were full siblings, meaning they shared the same father. the rest? They were probably consumed before they had a chance to grow.

Green and gold frogs – the power dynamics of post-sex cannibalism

Some creatures engage in so-called “sexual cannibalism” and consume their mates during or after copulation. As bizarre as it may seem, there is a good reason for this behavior: Women who practice sexual cannibalism are more likely to produce larger children.

Frogs green and gold bells (golden beaches)native to eastern Australia and now found on various Pacific islands such as New Zealand, were recently observed hunting adult males during the breeding season, described in a June 2024 study in Ecology and evolution.

While Golden beaches tadpoles often feed on each other, what made this study particularly interesting is that a unique case of adult-to-adult cannibalism was encountered in these usually docile frogs. Even stranger was a case where a male was eaten for performing a poorly executed mating ritual.

When it comes to sexual cannibalism in these frogs, the act becomes a pursuit of reproductive dominance. The female – by consuming the male – obtains essential nutrients for reproduction, thereby asserting her reproductive superiority over other females and improving the survival of her offspring.

A toad diet that controls their numbers

In environments where animal populations exceed available resources, cannibalism also serves as a natural form of population control, helping to reduce numbers to sustainable levels. The cane toad is a perfect example of this phenomenon.

Cane toads come from Central and South America (Rhinella Marina) they can have disastrous ecological consequences when they reach other regions. This is mainly due to their uncontrolled breeding and lack of natural predators. This means they can quickly overpopulate an area and become pests. Fortunately, however, they have developed behaviors that keep their numbers in check.

According to a March 2022 study, adult cane toads hunt their tadpoles when they detect a toxin released by tadpoles to protect themselves from predators. Ecology and evolution.

This cannibalistic behavior helps regulate population density and ensures that the limited resources available in their environment are sufficient for the remainder to survive. Although this behavior is unusual in their natural habitat, it is thought to have evolved as a natural form of population control in places with too many mouths to feed.

Cannibalism provides a unique window into animal life and survival strategies. Although it may seem drastic, the cannibalistic practices adopted by these animals demonstrate their remarkable resilience and ability to thrive in harsh conditions.

While cannibalism may be an exercise in survival for many in the animal kingdom, not everyone will find killing animals acceptable. Discover the power of your connection to the natural world with this quick test: Scale of connectedness with nature